In the past, as a technique that generates an optical pulse, a method is known in which a light is modulated to produce an optical frequency comb made up of a number of high-order frequency components, thereby turns the light into pulses, and furthermore, the optical pulse is compressed by using a dispersion compensator (for example, refer to PTL 1).
However, in the method of the related art, while it is possible to change the repetition frequency of an optical pulse, it is not possible to generate an optical pulse train with an arbitrary pattern.